Frame sizing dilemma

I've been trying out a few bikes at my LBS and am pretty settled on an 07 Rockhopper Comp, but am having trouble choosing a frame size - 17/medium or 19/large. When testing them out, the 17" felt pretty nice, but the guy at the shop said I looked a bit cramped and suggested I try a 19. So I tried a 19, and noticed how it stretched me out more, maybe a bit too much, but overall I felt the bike was a little bulkier and I preferred the 17. When I said I liked the 17 better the shop guy didn't seem sure it was the right size for me, but mentioned he could put a longer stem on it.

Anyways, from what I've read here, size seems like a pretty critical decision so I feel bad that I'm unsure. For what it's worth from someone new to MTB, if the guy hadn't said anything I would have happily got the 17. Anyone have tips? BTW: I'm 5' 9 1/2" tall and have a 33" inseam.

I'd go with the medium. I am currently riding a large frame hard rock and went through the same thing as you but with a large to Xlarge frame. I'm 6ft and 245lbs and the xl strtched me out to much and the large felt better. Went with the large. Happy i did. I'm not a professional fitter but see what they say as they will probably have more info on the matter.

For your height I'd go with the Medium. I got a large Rockhopper (19") because it was on clearance from my LBS. I doesn't feel overly stretched out but I'm looking to put a new stem on it. I think for you height (I'm not a professional at this) you'll be much more comfy on the 17".

I'm the same height and inseam. I don't ride Specialized, but am familiar with your dilemma having faced sizing choices recently. I ended up with a Medium Yeti frame (23" ETT) and with a DH stem it feels a little cramped as I prefer a streched out position.

Does the Rockhopper come with a layback seatpost? If not, you can add almost another inch of stretch to the M frame by using one.

Thanks for the responses. I went into the LBS again today, tried out some bikes, and wound up leaving with the 17" Rockhopper Comp :-) The 19" really seemed a bit more than I wanted to handle. The only other bike I considered for size was a 17.5" Trek 6500, but really, I couldn't tell the difference between the size on that and the Rockhopper. One thing I did do though was swap out for a 100mm stem to stretch things out a bit, which is actually what the Trek comes with. I'll see how that feels...

Being new to MTB (I used to BMX a bit), I'm somewhat wierded out by having my seat up so high. I adjusted as recommended by Specialized for my legs and I've got about 8 inches of seatpost showing. From the ground to the top of my seat is about 1/2" lower than the top of my stem... the seat still looks taller though for some reason. Any comments on seat height ?

Whew! I'm glad you stuck with the 17". I had the same dilema but with the Stumpjumper HT. I'm 5'9" with a 32" inseam. Good news for me was that the Stumpy comes with an 18" model, which I went with. It fits all fine and dandy, but after some experience on the bike, I still would prefer the 17", for it would give me better control. Good luck with the RH and post some pix!

I haven't had a chance to hit a trail with the fork yet, but I did some 2 ft drops on dirt and am pretty happy with it. Of course, this is my first suspension bike ever, so I really have no point of reference.